A switched capacitor is an electronic circuit element used for discrete time signal processing. Switched-capacitor circuits can be used, for example, as adders (or summers) in a sigma-delta modulator, which can be used in analog-to-digital and digital-to-analog converters, frequency synthesizers, switched-mode power supplies, and motor controls. In some examples, the switched-capacitor circuit utilizes an operational amplifier. An advantage of utilizing an operation amplifier is that it does not have gain decrease, due to the utilization of the operational amplifier. However, such an architecture has the disadvantage of a limited input voltage range and a nonlinear response. In other examples, the switched-capacitor circuit does not utilize an operational amplifier. Although such an architecture can have a greater input voltage range and a linear response, the architecture has the disadvantage of a gain decrease due to the capacitor ratio.
In order to improve the linearity of the sigma-delta modulator, it may be desirable to utilize a circuit architecture such that the distortion performance of the sigma-delta modulator is not adversely affected, i.e., the response is linear. Also, to maintain low offset characteristics of the sigma-delta modulator it may be desirable to have the switched-capacitor circuit perform such that it has minimal gain decrease.
Accordingly, new circuits and methods are desired to solve the above problems.